1. Field of the Invention:
This invention relates in general to the field of seismic prospecting and in particular to an apparatus for implanting and positioning a geophone assembly into the earth in a desired orientation and in a level condition.
2. Description of the Prior Art
In seismic exploration, sound waves are commonly used to probe the earth's crust as a means of determining the types and location of subsurface formations The earth's crust can be considered a transmission medium or filter whose characteristics are to be determined by passing sound waves through that medium In the reflection seismic method, sound disturbances are made at a transmission point at or near the earth's surface, and sound waves which are reflected from subsurface reflecting boundaries are detected by seismic detectors, e.g. geophones, which generate electrical signals at their outputs. Information relating to subsurface formations is contained in these electrical signals, and the signals are recorded in a form which permits analysis. Skilled interpreters can discern from the analysis the shape and depth of subsurface reflection boundaries and the likelihood of finding an accumulation of minerals, such as oil or gas.
In a typical seismic field recording system, the arrays of seismic detectors are located at regularly spaced intervals along that portion of the earth's surface under consideration. A typical seismic exploration system also includes a recording truck and a multi-pair of cable, which is used to connect the outputs of the detector rays to the recording truck. Typically, a pair of wires is "taken out" of the recording cable for appropriate connection to the output of each array. The location at which a given pair is taken out of the cable has been referred to by such designations as "receiver point", "receiver station", or "station". The data obtained at each receiver point from the output of an array of detectors forms a "channel" of information, which is provided to the recording apparatus for analysis and interpretation.
It is important in such exploration that each geophone in an array be placed in proper orientation with respect to the other geophones in the array and level with respect to the earth's surface. This is particularly important in view of the fact that recently detector arrays have been developed which utilize geophone assemblies which have focused directional characteristics, either in a single dimension or in multiple dimensions. These characteristics and a desire in the industry for increased accuracy in the precise determination of the location of subsurface formations have made accurate geophone positioning and placement a key requirement in the industry.